Steady advances are being made in understanding the functions of viral regulatory genes in virus replication and pathogenicity. However, there has been relatively little advance in attempting to exploit such regulatory proteins as antiviral targets. One goal of the meeting would be to stimulate discussion on what regulatory protein functions could be exploited for antiviral strategies. Several emerging studies suggest that HIV-1 replication may persist in the host despite suppression of virus replication to below detectable limits by current plasma-based viral RNA assays. Thus, highly active antiretroviral therapy in its current form appears to be incapable of eradicating these reservoirs. The task ahead is to identify the nature of the persistent reservoir and to develop alternate strategies to more effectively control virus replication. In an attempt to establish the underlying basis for lymphocyte depletion in HIV-1 infection, investigators are taking various approaches to evaluate various aspects of the hematopoetic function, lymphocyte maturation, lymphocyte turnover and compartmentalization. These approaches are providing a more complete understanding of how primate lentiviruses effect lymphocyte depletion. In addition, these studies are providing important information on the processes that regulate hemotopoiesis and lymphocyte function in humans, including immunocompromised HIV-1 infected individuals. We believe that the meeting format will provide a unique opportunity for scientists with interests in AIDS immunology, virology, and pathogenesis to be appraised of and to discuss the most exciting research developments and major problems in AIDS research. Such a forum does not exist outside of the National AIDS and Human Retroviruses meeting. However, the small size of the Keystone Conference allows the intimacy in which scientific ideas can be exchanged, and such an intimacy is not provided by the National AIDS meeting.